通過純粹的原生Android應用

Question

檢索android.os.Build ....系統屬性我有一個純粹的原生Android NDK應用程序，並且需要檢索的值，如： android.os.Build.MODEL

不幸我找不到如何解決這個問題的好例子？

Answer 1

NDK並不是要取代基於Java的API，而是要補充它。要獲得Build，必須在C/C++中找到它的私有實現，或者通過JNI提供來自Java的信息。

僞代碼：

android_main(struct *android_app){ 
    JNIEnv *env = android_app->activity->env; 
    jclass build_class = FindClass(env, "android.os.Build"); 
    jfieldID brand_id = GetStaticFieldID(env, build_class, "BRAND", "Ljava/lang/String;"); 
    jstring brand_obj = (jstring)GetStaticObjectField(env, brand_id); 
} 

Answer 2

我不認爲你可以遺憾的是做到這一點。您可以始終在VM中啓動，並在檢索要訪問的值後通過JNI跳轉到本地。

Answer 3

這些值很容易通過<sys/system_properties.h>中定義的接口在本地代碼中獲得，該接口自第一次NDK發佈以來一直存在。您只需要知道Java端使用的字符串標識符。幸運的是，使用開源操作系統，我們可以輕鬆找到這些操作系統。這是檢索型號名稱的一個工作示例。

#include <sys/system_properties.h> 

// 
// Public codes are defined in http://developer.android.com/reference/java/lang/System.html#getProperty(java.lang.String). 
// Codes below are defined in https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/java/android/os/Build.java. 
// Items with * are intended for display to the end user. 
// 

#define ANDROID_OS_BUILD_VERSION_RELEASE  "ro.build.version.release"   // * The user-visible version string. E.g., "1.0" or "3.4b5". 
#define ANDROID_OS_BUILD_VERSION_INCREMENTAL "ro.build.version.incremental"  // The internal value used by the underlying source control to represent this build. 
#define ANDROID_OS_BUILD_VERSION_CODENAME "ro.build.version.codename"   // The current development codename, or the string "REL" if this is a release build. 
#define ANDROID_OS_BUILD_VERSION_SDK   "ro.build.version.sdk"    // The user-visible SDK version of the framework. 

#define ANDROID_OS_BUILD_MODEL    "ro.product.model"     // * The end-user-visible name for the end product.. 
#define ANDROID_OS_BUILD_MANUFACTURER  "ro.product.manufacturer"   // The manufacturer of the product/hardware. 
#define ANDROID_OS_BUILD_BOARD    "ro.product.board"     // The name of the underlying board, like "goldfish". 
#define ANDROID_OS_BUILD_BRAND    "ro.product.brand"     // The brand (e.g., carrier) the software is customized for, if any. 
#define ANDROID_OS_BUILD_DEVICE    "ro.product.device"     // The name of the industrial design. 
#define ANDROID_OS_BUILD_PRODUCT    "ro.product.name"     // The name of the overall product. 
#define ANDROID_OS_BUILD_HARDWARE   "ro.hardware"      // The name of the hardware (from the kernel command line or /proc). 
#define ANDROID_OS_BUILD_CPU_ABI    "ro.product.cpu.abi"    // The name of the instruction set (CPU type + ABI convention) of native code. 
#define ANDROID_OS_BUILD_CPU_ABI2   "ro.product.cpu.abi2"    // The name of the second instruction set (CPU type + ABI convention) of native code. 

#define ANDROID_OS_BUILD_DISPLAY    "ro.build.display.id"    // * A build ID string meant for displaying to the user. 
#define ANDROID_OS_BUILD_HOST    "ro.build.host" 
#define ANDROID_OS_BUILD_USER    "ro.build.user" 
#define ANDROID_OS_BUILD_ID     "ro.build.id"      // Either a changelist number, or a label like "M4-rc20". 
#define ANDROID_OS_BUILD_TYPE    "ro.build.type"      // The type of build, like "user" or "eng". 
#define ANDROID_OS_BUILD_TAGS    "ro.build.tags"      // Comma-separated tags describing the build, like "unsigned,debug". 

#define ANDROID_OS_BUILD_FINGERPRINT   "ro.build.fingerprint"    // A string that uniquely identifies this build. 'BRAND/PRODUCT/DEVICE:RELEASE/ID/VERSION.INCREMENTAL:TYPE/TAGS'. 


char model_id[PROP_VALUE_MAX]; // PROP_VALUE_MAX from <sys/system_properties.h>. 
int len; 
len = __system_property_get(ANDROID_OS_BUILD_MODEL, model_id); // On return, len will equal (int)strlen(model_id).